How does a exchange work?

Would you like to know how a exchange works? My focus would be on the technical side.
Does every exchange have a Bitcoin Core installation?
Does every exchange have a single wallet, or are there multiple wallt’s?

Hey,
I actually don’t really know the answer to that. I think exchange have several walletr that they keep their funds in. Most of the funds are in cold storage (i.e. offline wallets like hardware wallets) and aroudn 20% of the funds are in “hot wallets” (i.e. wallets connected to the internet) so that they will have liquidity. However I can’t verify this info, it’s just stuff I’ve picked up along the way.